Sulfonation process



Patented Oct- ,5, 1948 Edmond L. dOnville, Chicago, 111., andDonald E. Barney, Hammond, Ind., allignorl to Standard Oil Indiana Company, Chicago, 111., a corporation of No Drawing. Application May 2'1, 1943,

-. Serial No. 488.7024

This invention relates to improved sulfonation processes. proved processes for the sulfonation of mixtures comprising alkyl aromatic hydrocarbons which form preferentially water soluble sulfonic acids upon sulfonation and alkyl aromatic hydrocarbons which form preferentially'oil soluble sul-' fonic acids upon sulfonation.

Sulfonated alkyl aromatic hydrocarbons have found extensive application in industry, especial-l ly as wetting, washing and emulsifying agents. The length of the alkyl chain has been found to exert a remarkable influence on the properties of the sulfonates produced from alkyl aromatic hydrocarbons. Thus it has been found that sodium alkylbenzene sulfonates are preferentially water soluble and have a maximum detergenc'y when the alkyl group contains about to about 14 carbon atoms. Higher alkyl benzene sulfonates containing more thany16 carbon atoms in the alkyl group are preferentially oil-soluble and, in many respects, resemble the preferentially oil-soluble sulfonates obtainable from petroleum oils by treatment with fuming sulfuric acid. The latter are known in the petroleum refining art as mahogany soaps.

The mahogany-type sulfonic acids and salts are useful in a wide variety of applications to which mahogany acids and salts have been adapted, such as fat-hydrolysis, emulsification of mineral oils with water or aqueous solutions, in insecticidal spray oils, as textile as-- sistants, and as rust inhibitors in slushing oils or greases.

It is highly desirable to be able to produce alkyl aromatic sulfonie acids which are preferentially water soluble and substantially free of preferentially oilsoluble alkyl aromatic sulfonic acids, as well as preferentially oil soluble alkyl aromatic sulfoni'c acids substantially free of preferentially water soluble alkyl aromatic sulfonic acids from .a crude mixture of alkyl aromatic hydrocarbons which yields both preferentially oil soluble and preferentially water soluble alkyl More particularly. it relates to im-' higher alkyl aromatic 4 Claims. (Cl. 260-505) "2 aromatic sulfonic acids upon non-selective sulfonation.

The desirability of segregating preferentially water soluble alkyl aromatic sulfonic acids on the one hand, and preferentially oil soluble alkyl aromatic sulfonic acids on the other, is dictated in large measure by the uses which each group of sulfonic acids or their salts is adapted best to fulfill. Formerly, alkyl aromatic hydrocarbons whose monosulfonic acids\ are preferentially water soluble were carefully fractionated, usually under vacuum, in advance of sulfonation to segregate them from alkyl aromatic hydrocarbons whose monosulfonic acids are preferentially oil soluble. Alternatively, methods of synthesis were employed which would. yield substantially only alkyl aromatic hydrocarbons whose monosulfonic acids are either preferentially water soluble or referentially oil soluble, and not mixtures of both types ofalkyl aromatic hydrocarbons. Both of these procedures are laborious, time-consuming and expensive. By the process of our invention these procedures of preliminary purification of feed stock or the preparation of a feed stock of narrow molecular weight range are avoided.

It is an object of our invention to provide an improved process for the manufacture of alkyl aromatic sulfonic' acids and salts containing alkyl groups of a narrow, selected molecular weight range from crude, .wide boiling-range mixtures of alkyl aromatic hydrocarbons. Another object of our invention is to provide a process which obviates the necessity of purifying crude alkyl aromatic, hydrocarbons prior to sulfonation to obtain alkyl aromatic hydrocarbons wherein the alkyl groups are restricted to a relatively narrow molecular weight range.

A further object of our invention is to provide Yet=another object of ourinvention is to provide a selective sulfonation process which avoids the necessity of segregating a selected feed stock by distillation from a- 'crude mixture of alkyl aromatic hydrocarbons".

An additional object of our invention is to provide a selective sulfonation process wherein a.

. mixture .of alykl aromatic hydrocarbons capable of yielding both preferentially water soluble and r erentially oil soluble alkyl aromatic sulfonic acids upon non-selective sulfonation is sulfonated to yield preferentially water soluble alkyl aromatic sulfonic acids; to. the substantial exclusion of preferentially oil soluble alkyl aromatic sulionic acids.

Yet another object of our invention is to provide a two-stage sulionation process in the first stage of which sulfonation of alkyl benzene hydrocarbons containing less than 17' carbon atoms in the alkyl group is selectively effected and in the second stage of which sulfonation of alkyl benzene hydrocarbons containing at least 17 carbon atoms in the alkyl group is effected.

A further object of our invention is to provide a process for the preparation of pure, preferen-.

tially oil-soluble alkyl aromaticsulfonic acids and soaps from a mixture predominating in alkyl aromatic hydrocarbons adapted to yield preferentially oil-soluble allwl aromatic sul'fonic acids upon monosulfonation and containing aminor proportion of alkyl aromatic hydrocarbons adapted to yield preferentially water-soluble alkyl aromatic sulfonic acids upon monosulfonation.

We have found that mixtures of alkyl aromatic hydrocarbons which yield both preferentially water-soluble and preferentially'oil-soluble alkyl aromatic suifonic acids upon non-selective sulfonation can be selectively sulfonated to yield substantially only preferentially water-soluble alkyl aromatic sulfonic acids by proper choice of the initial and final sulfuric acid concentrations and other reaction variables such as temperature, rate of agitation of the reaction mixture and acid: feed stock ratio used in sulfonation.

We have also'found that the unreacted aromatic hydrocarbons whose monosulfonic acids are preferentially oil soluble can be separated from the selective sulfonation reaction mixture and sulfonated with sulfuricacid having a higher initial concentration than thatused in selective sulfonation to produce" sulfonic acids having many characteristics in common with mahogany" acids. I

- An especially desirable application of our proc'- ess may be made to feed stocks predominating in higher alkyl aromatic hydrocarbons, whose monosulfonic' acids are preferentially oil soluble, particularly alkyl benzen hydrocarbons containing 17 or more carbon atoms in the-alkyl group,- and containing a minor proportion, e. 3. about 5 to about 15 percent byvolume, of lower alkyl aromatic hydrocarbons whose monosulfonic acids are preferentially water soluble, particularly alkyl benzene hydrocarbons containing less than 17 carbon atoms in the alkyl group. Feed stocks of this nature are sulfonated to produce-preferentially oil soluble sulfonic acidsand soaps substantially free of preferentially water soluble alkyl aromatic sulfonic acids. For certain purposes it is highly desirable that oil soluble alkyl aromatic suli'onic acids be substantially free 01 the lower, preferentially water soluble alkyl aromatic sulfonic acids containing less thanl'l carbon atoms in thealky'l group.

. y I v tim Qmsinventioh can be applied tdagizk variety 'of alkyl aromatic compounds. The aromatlcnucleus can he's for example, benzene, toluene, xylenes, cuxnene, naphthalene, methyl naphthalenes, ethylnaphthalenes, isoptopyl or other alkvl naphthalenes, 'diphenyl, dinlhenyls. anthracene and alhyl anthracenes o the natural occurring or artiflcally prepared mixtures. Halog nitro, hydroxy. or other derivatives of the above aromatic hydrocarbons may also be sulfonated by ourprocess. The aromatic nucleus may be alkylated with a mixture of alkylating agents wherein th length of the alhl group can vary from about 3 to about 30, 40, 50 carbon atoms or more to produce mixtures of alkyl aromatic compounds yielding both preferentially water-soluble and preferentially oil soluble sulfonic acids upon non-selective milfonation. The alkylatingagents may be haloparafl'ins. oleflns, olefin polymers,alkyl sulfates. aliphatic alcohols, or aliphatic esters of wide molecular weight range. Any method of securing a mixture of alkyl aromatic hydrocarbons wherein the alkyl chain length varies over a wide range issa'tisfactory for the purposes of our invention.

Alkylation may be eflected with -100 percent sulfuric acid, aluminum chloride activated with a trace of hydrogen chloride, hydrogen fluoride, boron fluoride and other known alkylation catalysts.

A highly satisfactory method of preparing a crude mixture or alkyl aromatic hydrocarbons for the purposes of our invention comprises alkylating an aromatic hydrocarbon with an olefin poly- ..mcr. Suitable olefin polymers are those of ethylene, propylene, the butylenes, pentenes and the like, or mixtures thereof, preferably of wide boiling range and varying in chain length in the range of about C3 to about Can or more, preferably about Clo to about C20. We may also use olefin co-polymers produced by co-polymerizlng two or more of the above or similar olefins.

We hav found that propylene polymers having a wide boiling range and correspondingly wide molecular weight rangeare particularly suitable alkylating agents for aromatic hydrocarbons and produce ,a-highly satisfactory feed stock for our sulfonation processes. Propylene can be polymerized by passingit in the liquid phase thrown a pool of dispersed aluminum chloride catalyst to y eld a polymer of relatively wide boiling and molecular weight ranges. We may, but preferably do not, use. the total polymer. We prefer to use the light ends of the polymer which would normally be considered a waste product, since they boil too high for use in gasoline and are too volatile and non-viscous for inclusion in lubricating oil. Th boiling range of these light ends will vary depending upon the conditions used in polymerization and upon thedegree that the total polymer is reduced by distillation. Table I contains. the A. S. T. M. distillations and other inspections of-steam distillates from total propylene polymers. Such waste products are suitable starting materials for the alkylation of aromatic compounds, preferably hydrocarbons. to produce alkyl aromatic mixtures for our sulfonation processes. Refinery propylene was polymerized by the use of an aluminum chloride catalyst at the temperatures shown in Table I and the total polymerizate was distilled with fire and steam. In Table I, under tests A and C the first 10% of the polymer to be distilled was segregated and sublected to the following inspections: A. S. '1. M.

auaeae 3. excess ot'benze'ne was us dwlth respect to the 4 polymer. Accordinlly. the p ly w rely consumed and the sole remaining problem was to Separate benzene from the alkylated benzene.

Tart: I

A B O Tem oi Poiymeriza 3, '85 85 115 Wt. Per cent Distilled Overhead l 5 Per cent 'lem Per cent Tem Per cent 'lem on r? on "r? on r? Initial s10 mam 114 Initial 35s 10 384 10 354 10 402 416 20 416 20 432 A. B. T. M. Distilla- 442 30 454 30 452 tion 466 40 494 40 474 488 50 518 50 492 506 60 538 60 52) 70 526 70 550 70 540 80 552 80 570 80 664 90 584 90 600 90 606 i 'Max. 628 Max. 620 Max. 656

Bromine No 79 69 x 67 N l 4512 l 4410 1. 4499 Gravity, A. P. I.. .8 .9 43.8

' In our process the total steam distillate or relatively wide boiling fraction of propylene polymer is alkylated. A close fractionation of the polymer is not necessary. However, in the alkylation of benzenes, we prefer to employ a polymer of which a substantial proportion boils within the range of about 300 to about'500 F.

.By way of example, descriptions are given of the alkylation of benzene with propylene polymers. The alkylation conditions, yields and other pertinent data are shown in Table II:

Teena II Benzene was stripped from thealkylate merely by heating the mixture and passing steam or air as a stripping gas through the alkylate to remove the benzene which was thereafter condensed from the vapor stream. I

We have found that crude alkylates obtained from benzene and propylene polymers, even' when prepared from narrow boiling polymer fractions, have a wide boiling range'and contain high boiling parafllns and other impurities in-appreciable proportions.

- Alkylation oi Benzene with Propylene Polymers Mols polymer rt ies oi Crude Alkyla D Specific Dispersion gsravity, A. P. I.

Per cent Theory Vol. r cent Crude Alky ate Based on Polymer The polymer used in runs 1, 2, and 3 of Table II was polymer A of Table I. The polymer used in run 4 of Table II was the first 36 weight percent distilled overhead of a propylene polymer prepared in the same fashion as polymer A of Table I. The polymer used in runs 5 and 6 was C of Table I. The average molecular weights of the polymers used was determined bya standard method, viz., the A. W. Francis bromine number method, Ind. Eng. Chem. 18, 821 (1926). In all the runs except number 1, a considerable molar soaps from our selective sulfonation process are eilective wetting agents, wetting times varying from 5 to 15 seconds. for 0.5% solutlonsinwater.

Tannin Sallmtioa of raised alkvlates RunNo. a B c n 182 200 no no m 100 m :00

l (3 13 (u so so so 80 as us as 240 a: ms 130 is: 8..., 38 it it 0MB ,8

iesofOilResidue: P. oLPercentofOharge g of 53 iii 0 vii s.r.r. 'us a r) H 111 Mechanical. :sir.

'Puriiiedsoap.

In general we have found that alkyl aromatic compounds whose monosulfonic acids are preferentially water soluble, and particularly alkyl benzenes containing less than 17 carbon atoms in the alkyl group, may be selectively sulfonated in admixture with higher allryl aromatic compounds whose monosulfonic acids are preferentially oil soluble by the use of about 88 to about 98 weight percent sulfuric acid at temperatures in the approximate range of about 50 to about 150 F. The initial sulfuric acid strength and other reaction conditions are so adjusted in our process that selective sulfonation is effected only of those alkyl aromatics whose monosulfonic acids are preferentially water soluble. In particular instances it may be necessary to use somewhat stronger or more dilute sulfuric acid than indicated by the range of about 88 to about 98 weight percent sulfuric acid. Weprefer to use about 0.2 to about 2.0 volumes of acid per volume of feed stock. The reaction period may vary from about 1 to about 20hours or more, depending upon the nature of the specific feed stock, acid strength and other reaction conditions. It is desirable to maintain the sulfonation mixture in a state of agitation during the reaction Period; agitation may be effected by the use of any of a large variety of known methods, but we prefer to use a mechanical agitator or to bubble an inert gas, such as air, through the reaction mixture.

Our selective sulfonation depends upon the use of the proper strength and amount of sulfuric acid. Thus, in the sulfonation of alkyl benaenes it is important that the acid strength be such that only allryl benzenes containing fewer than 17 carbon atoms in the alkyl groups are sulfonated. It is likewise important that the amount of acid be sufficient so that the spent acid-is of sufficient strength to retain in solution the alkylbenzene sulfonic acids containing fewerthan about 9 carbon atoms. We have found that spent acids having specific gravities within the range of from about 1.70 (78% acid) to about 1.80 (88% a'cid) perform this function satisfactorily. The specific gravity of the acid in our selective sulfonation process, as applicable to alkyl benzenes, decreases 'from an initial of about 1.83 to a gravity within the above range.

Followi'ng selective suifonation, the reaction products may be separated by a variety of methods. e. g. by solvent extraction, dilution with water and stratiflcation, etc. We prefer to allow the reaction mixture to stratify without adding water 8 or other diluting medium thereto. Three strata group is toosmall (less thanil carbon atomsin the case of alkyl benzene sulfonic acids) for good detergents.

It shouid'be noted that the sulfonic acids which are preferentially acid soluble and which are recoverable by dilution of the acid layer yield soaps which are inferior detergents. This emphasiaes the necessity of controlling the final as well as the initial acid strength in our selective suifonation process.

The upper stratum consists of unsuifonated alkyl aromatics which form preferentially oil soluble sulfonic acids upon monosulfonation, as well as paraiiins and dialkyl aromatic hydrocarbons.

The middle stratum consists predominantly of alkyl aromatic sulfonic acids which are preferentially water soluble. The middle stratum obtained by stratification of the reaction mixture when aikyi benzenes are selectively sulfonated consists of allryl benzene sulfonic acids in which the alkyl group contains from 9 to 16 carbon atoms, while the upper stratum contains alkyl benzenes in which the alkyl group contains 17 or more carbon atoms. There is also in the middle stratum considerable dissolved sulfuric acid. If sufficient time is allowed, for example about 5 hours. for complete stratification. no oil remains in the middle stratum. Traces of preferentially oil soluble sulfonic acids are likewise absent since these are selectively extracted by the upper stratum.

Since detergents of this type are most eifective when compounded with sodium sulfate in the proportion of about 40% soap to 60 salt by weight, it is not necessary to separate the sulfonic acid from the sulfuric acid. The middlestratum can be neutralized with strong caustic solution, the soap-salt mixture dried at about 260 F. and additional sodium sulfate added.

When pure soap is desired we prefer to add to the middle stratum about an equal volume of water. This results in the separation of a relatively pure sulfonic acid solution upper stratum and a strong sulfuric acid lower stratum. The upper stratum is neutralized and alcohol added to precipitate the salt. Thereafter the alcohol is evaporated and the residue dried.

' The residual oils produced in our selective suifonatlon process consist in maior part of higher alkyl aromatic hydrocarbons which form preferentially oil soluble sulfonic acids upon monoculfonation. In addition they contain relatively small proportions of high boiling parafiin hydrocarbons and complex aromatic products. We have found that residual oils from our selective sulfonation process may be readily sulfonated by the use of sulfuric acid containing at least about weight percent of sulfur trioxide to produce preferentiaily oil-soluble sulfonic acids and soaps having valuable emulsifying properties.

By way of example, a composite sample of residual oils which resisted sulfonation with 96 weight percent sulfuric acid in the selective sulfonation of a mixture of alkyl benzenes containing less than 17 carbon atoms in the alkyl group and at least 17 carbon atoms in the alkyl group was prepared and sulfonated as follows: parts are by weight. seventy-five parts of the composite sample were cooled to about 40 R, 15 parts of 96 weight percent sulfuric acid were added and the mixture was agitated vigorously.

All

The mixture was maintained at a temperaturebetween 35 and 40 F. while 90 parts of 30% fuming sulfuric acid were added dropwise over a period of three hours. The reaction mixture was then allowed to warm up and agitation was continued for one hour. It was again cooled, diluted with 40 parts of water and allowed to stratify. A lower acid stratum was withdrawn. The upper stratum was diluted with 90% alcohol and neutralized with caustic solution. The alcoholic stratum was extracted with an equal volume of hexane. Both the alcoholic and hexane strata were reduced in volume by distillation of the solvent therefrom. The alcoholic stratum yielded 31 parts of a solid soap. The hexane stratum yielded 56 parts of an oil-soap mixture which is preferentially. soluble in oil and has good emulsifying properties. It will be apparent from the foregoing description that we have discovered a novel and highly useful selective sulfonation process and products. We have also discovered and successfully applied a unitary process comprising a selective twostage sulfonation technique to mixtures of alkyl aromatic hydrocarbons to secure the most rational utilization thereof, while obviating expensive and laborious fractionation of the feed stock prior to sulfonation.

We claim:

l. The process of sulfonating a mixture of alkyl aromatic hydrocarbons which yields both preferentially water-soluble and preferentially oil-soluble alkyl aromatic sulfonic acids upon nonselective sulfonation, which comprises contacting said mixture with at least 20 volume percent,

. based on said mixture, of sulfuric acid having an initial strength between about 88 and about 98 weight percent of sulfuric acid at a temperature between about 50 F. and about 150 F. for a period of at least one hour to effect substantial preferential sulfonation of alkyl aromatic hydrocarbons whose sulfonic acids are preferentially water-soluble, separating preferentially watersoluble alkyl aromatic sulfonic acids from the sulfonation reaction mixture, separating residual alkyl aromatic hydrocarbons from the sulfonation reaction mixture, and sulfonating said residual alkyl aromatic hydrocarbons with fuming sulfuric acid to produce preferentially oil-soluble alkyl aromatic sulfonic acids. I

2. The process of sulfonating a mixture of alkyl benzene hydrocarbons which yields both preferentially water-soluble and preferentially oil-soluble alkyl benzene sulfonic acids upon nonselective sulfonation, which comprises contacting said mixture with at least 20 volume percent, based on said mixture, of sulfuric acid having an initial strength between about 88 and about 98 weight percent of sulfuric acid at a temperature between about 50' I". and about 150' I". for a period of at least one hour to effect substantial preferential sulfonation of alkyl benzene hydrocarbons whose sulfonic acids are preferentially v l0 water-soluble, separating preferentially watersoluble alkyl benzene sulfonic acids from the sulfonation reaction mixture, separating residual alkyl benzene hydrocarbons from the sulfonation reaction mixture, and sulfonating said residual alkyl benzene hydrocarbons with fuming sulfuric acid to produce preferentially oil-soluble alkly benzene sulfonic acids.

3. The process of sulfonating a mixture of alkyl benzene hydrocarbons having alkyl groups containing less than 17 carbon atoms and alkyl groups containing at least 17 carbon atoms, which comprises contacting said mixture with at least 20 volume percent, based on said mixture, of sulfuric acid having an initial strength between about 88 and about 98 weight percent sulfuric acid and a final strength between about 78 and about 88 weight percent sulfuric acid at a temperature between about 50" F. and about 150 F. for a period of at least one hour to eifect substantial preferential sulfonation of alkyl benzene hydrocarbons containing less than 17 carbon atoms in the alkyl group, separating sulfonated hydrocarbons from the sulfonation reaction mixture, separating unsulfonated alkyl benzene hydrocarbons containing at least 17 carbon atoms in the alkyl group from the sulfonation reaction mixture and subjecting said unsulfonated allgvl benzene hydrocarbons to sulfonation with 8111-, furic acid containing at least 80 weight percent sulfur trioxlde for a period of time suflicient to effect substantial sulfonation to produce preferentially oil-soluble alkyl benzene sulfonic acids, and separating said preferentially oil-soluble alkyl benzene sulfonic acids from the last named sulfonation operation.

4. The process of claim 1 wherein the final sulfuric acid strength in the first sulfonation stage is between about 78 and about 88 weight percent sulfuric acid.

EDMOND L. rOUvILL-E.

DONALD E. BURNEY.

REFERENCES CITED The following references are of record in the file of thispatent:

UNITED STATES PATENTS Number Name Date 1,787,408v Posplech Dec. 80, 1980 1,901,007 Guenther Mar. 14, 1983 2,232,117 Kyrides Feb. 18, 1941 2,282,118 Kyrldes Feb. 18, 1941 2,238,408 Flett Mar. 4, 1941 2,250,010 Buc Sept. 23, 1941 2,267,720 l'lett Dec. 30, 1941 2,304,782 Flett Dec. 12. 1944 FOREIGN PATENTS- Number Country Date 410,379 Great Britain Sept. 0, 1984 

